Malaria is caused by the Plasmodium parasite. The parasite can be spread to humans through the bites of infected mosquitoes.
There are many different types of plasmodium parasite, but only 5 types cause malaria in humans.
- Plasmodium falciparum – mainly found in Africa, it's the most common type of malaria parasite and is responsible for most malaria deaths worldwide
- Plasmodium vivax – mainly found in Asia and South America, this parasite causes milder symptoms than Plasmodium falciparum, but it can stay in the liver for up to 3 years, which can result in relapses
- Plasmodium ovale – fairly uncommon and usually found in West Africa, it can remain in your liver for several years without producing symptoms
- Plasmodium malariae – this is quite rare and usually only found in Africa
- Plasmodium knowlesi – this is very rare and found in parts of southeast Asia
The plasmodium parasite is spread by female Anopheles mosquitoes, which are known as "night-biting" mosquitoes because they most commonly bite between dusk and dawn.
If a mosquito bites a person already infected with malaria, it can also become infected and spread the parasite on to other people. However, malaria can't be spread directly from person to person.
Once you're bitten, the parasite enters the bloodstream and travels to the liver. The infection develops in the liver before re-entering the bloodstream and invading the red blood cells.
The parasites grow and multiply in the red blood cells. At regular intervals, the infected blood cells burst, releasing more parasites into the blood. Infected blood cells usually burst every 48-72 hours. Each time they burst, you'll have a bout of fever, chills and sweating.
Malaria can also be spread through blood transfusions and the sharing of needles, but this is very rare.